DC MOTOR MCQS SET 12

DC MOTOR MCQS SET 12

1. Which of the following loss in a D.C. generator is dissipated in the form of heat?
(a) Mechanical loss
(b) Core loss
(c) Copper loss
(d) All of the above 

Ans:  d

2. Which of the following losses are significantly reduced by laminating the core of a
D.C. generator ?
(a) Hysteresis losses
(b) Eddy current losses
(c) Copper losses
(d) Windage losses 

Ans:  b

3. The total losses in a well-designed D.C. generator of 10 kW will be nearly
(a) 100 W
(b) 500 W
(c) 1000 W
(d) 1500 W 

Ans:  b
 

4. The condition for maximum efficiency for a D.C. generator is
(a) eddy current losses = stray losses
(b) hysteresis losses = eddy current losses
(c) copper losses = 0
(d) variable losses = constant losses

Ans:  d

5. D.C. generators are normally designed for maximum efficiency around
(a) full-load
(b) rated r.p.m.
(c) rated voltage
(d) all of the above
Ans:  a

6. In a D.C. generator, the iron losses mainly take place in
(a) yoke
(b) commutator
(c) armature conductors
(d) armature rotor 

Ans:  d

7. D.C. generators are installed near the load centres to reduce
(a) iron losses
(b) line losses
(c) sparking
(d) corona losses 

Ans:  b

8. The purpose of retardation test on D.C. shunt machines is to find out
(a) stray losses
(b) eddy current losses
(c) field copper losses
(d) windage losses 

Ans:  a

9. Which of the following tests will be suitable for testing two similar D.C. series motors of large capacity?
(a) Swinburne's test
(b) Hopkinson's test
(c) Field test
(d) Brake test 

Ans:  c

10. Hopkinson's test on D.C. machines is conducted at
(a) no-load
(b) part load
(c) full-load
(d) overload 

Ans:  c